1. Field of the Invention
This invention relates to a solar system for a motor vehicle with a motor vehicle roof and a motor vehicle interior, especially a solar cover, the solar system has a solar generator and a DC/DC converter unit, where the solar system switchably supplies a power consuming device in the motor vehicle and recharges a motor vehicle battery in the motor vehicle.
2. Description of Related Art
German Patent DE 198 39 711 discloses a solar system in which the DC/DC converter has two different outputs which lead to a fan motor or the motor vehicle battery, the DC/DC converter being provided with a battery charging function which results in that a fixed basic amount of electric power generated by the solar generator is supplied to the motor vehicle battery and the amount of electric power generated by the solar generator which exceeds this basic amount is supplied to the fan motor. It is not further explained how impedance matching to two power consuming devices with different impedance, i.e. the motor vehicle battery and the fan motor, is to take place.
Published European Patent Application EP 0 861 746 A1 corresponding U.S. patent application Ser. No. 09/031,062 discloses a similar solar system in which switching between the supply of the motor vehicle battery and of the fan motor takes place automatically, and the automatic switching can be overridden by a manually activated switch. Here too, there are separate outputs for the motor vehicle battery and the fan motor. There are no details here with regard to impedance matching.
Published German Patent Application DE 36 10 767 A1 discloses a solar system for a motor vehicle in which the solar generator comprises at least two solar cell units which are series connected by means of a changeover switch for battery recharging and which can be connected in parallel for supply of a fan blower. There is no impedance converter.
German Patent DE 195 27 740 C1 corresponding U.S. Pat. No. 5,779,817 discloses impedance matching in a solar system for a motor vehicle by selective parallel connection or series connection of strings of solar cells in order to selectively operate a fan motor or recharge a vehicle battery.
The object of this invention is to devise a solar system for a motor vehicle which in as simple a manner as possible with as few terminal contacts as possible allows impedance-matched supply both of a power consuming device in the motor vehicle and also the motor vehicle battery.
This object is achieved by a solar system for a motor vehicle with a motor vehicle roof and a motor vehicle interior, where the solar system has a solar generator, and a DC/DC converter unit, where the solar system switchably supplies a power consuming device in the motor vehicle and recharges a motor vehicle battery in the motor vehicle, where the DC/DC converter unit comprises a first and a second DC/DC converter, the DC/DC converter unit is optimized with respect to the supply function of the power consuming device and the recharging function of the vehicle battery, and where a changeover unit acquires a voltage at an output of the DC/DC converter unit and the changeover unit switches the output depending on the acquired voltage to the first and the second DC/DC converter. In this approach, it is advantageous that the impedance converter unit has only one output and still enables optimized impedance matching both for supply of the power consuming device and also the battery. In this way, the number of required electrical contacts can be minimized and by integration of the two impedance converters into a single unit, money and installation space can be saved. Furthermore, incorporation into the motor vehicle can be made very flexible since almost no additional components are necessary in the motor vehicle. The invention is described by way of example below with reference to the accompanying drawings.